At European Watch Company, we guide thousands of customers through their purchase decisions. These are five mistakes we see all the time: The Box-and-Papers Trap on the Wrong ReferencesThe logic seems airtight: original box and papers prove authenticity, establish provenance, and signal that the watch was properly owned. Why wouldn't you pay up for them?The answer is that you should, on the right references. The mistake is applying that logic indiscriminately, regardless of whether the specific watch actually rewards it at resale.The premium is real. Across the secondary market, complete documentation (box, warranty card, chronometer certificate, any service receipts) typically adds 13 to 23 percent to resale value. For major references from Rolex, Patek Philippe, and Audemars Piguet, that figure can reach 20 to 35 percent. If you are buying a steel Rolex sports reference or a Patek Nautilus and you have the option to pay up for a full set, the market will pay you back.